Study On The Key Technology Of Lycopene Industrialization In Saccharomyces Cerevisiae

Lycopene,an important carotenoid,can be applied in many areas due to its significant benefits in antioxidant activities,anti-cancer and cardiovascular disease prevention.Since there are still several limitations involved in large-scale commercialization of lycopene,such as low production capacity,limited resources,environment influence,inefficient technology and high cost,developing a more efficient and green manufacturing technology is crucial to break through the bottleneck in lycopene industrialization.In the study,taking a constructed Saccharomyces cerevisiae Sy BE?Sc14D14 as candidate strain,the lycopene yield is greatly improved by optimization of fermentation process and metabolomics research.Lycopene titer is successfully increased from 2.57 g/L to 7.01 g/L on 50 L fermenter.Meanwhile,the lycopene extraction,refining,recycling technology of wastewater and biomass residue was also studied accordingly.Finally,the scaling-up process of lycopene produced by S.cerevisiae was accomplished in the 12 m~3fermenter,the lycopene crystal was obtained with the purity of lycopene attaining 96.94%.The application research of lycopene products in laying fowl was also accomplished.Through correlation analysis between operation parameters and cell physiology,the key controlling points,such as dissolved oxygen,p H control,carbon and nitrogen source supplementation was identified.By combinatorial optimization of above controlling points,lycopene titer was enhanced from 2.57 g/L to 5.20 g/L in 50 L fermenter.It was also observed that glycine,glutamate,citric acid and acetic acid accumulations had significant influence on lycopene output.Subsequently,a comprehensive strategy was developed for lycopene production,leading to the highest reported lycopene titer at 7.01 g/L.Biomass pretreatment and extraction process was also explored accordingly.Spray drying process was set to get the dry biomass.Then,diverse ways of cell breaking were investigated,the result indicates that grinding and enzymatic hydrolysis can break down cell walls more efficiently.It was also found that the optimal amount ratio of extraction solvent to dry biomass weight is 50:1.The extraction yield is up to90.7%using the above constructed pretreatment and extraction process.The optimal crystallization process is 4?for crystallization,followed with ethanol washing for 3times at 50?and the yield of crystallization is 95.42%.In total,the purity of lycopene crystals is 96.94%,and the total yield of lycopene extraction is 86.5%.A continuous recycling strategy for utilizing wastewater,biomass residue and D-galactose was developed based on the enzymatic hydrolysis pretreatment process,in which fermented broth and biomass residue was used as feedstock for next batch.The mean lycopene titer attains 5.88±0.15 g/L after 3 recycles in 70 L fermenter,which is 22.25%higher than the start batch.It was also shown that the lowest unit product cost(29.6%lower than the start batch)was obtained by economic analysis after 4 recycles,in which the chemical oxygen demand(COD)discharge in wastewater decreases by 64.0%.Our study developed an environment friendly process of lycopene production for future commercialization.Consequently,the fermentation process was successfully scaled-up at 12 m~3fermenter with average lycopene output at 5.2 g/L.And then the biomass powder was tested in laying hens to investigate the coloring effect on eggs.The result showed that the quality and color of eggs was significantly improved by adding 150 mg/kg lycopene in the feed.